Entropion is an abnormality resulting in inversion (inward turning) of the eyelid margin. Entropion causes irritation to the exposed surface of the eyeball. Entropion can damage conjunctival and corneal surface which may lead to corneal abrasion, scarring, corneal thinning or neovascularisation. Advanced cases may develop corneal ulceration or even perforation.
Entropion may be of following main types:-
- Acute spastic
Though entropion can affect all ages, this is more common in older adults.
Involutional entropion patients are often elderly people and may be having significant comorbities (two or more diseases existing together).
Kanski,Jack J. Clinical Ophthalmology, A Systematic Approach .Third Edition.UK. Butterworth Heinemann, 1994.
Symptoms are due to irritation of anterior ocular (pertaining to eye) surface, being produced by inward turning of eyelid margin.
Patient may present with:-
- Foreign body sensation in eye.
- Irritation of eyes due to pseudotrichiasis (inward turned eyelashes due to entropion).
- Redness of eyes.
- Tearing/ watering of eyes.
- Eye discharge.
- Pain in eyes.
- Photophobia (intolerance) to light.
- Corneal abrasion.
- Corneal ulceration.
- Symblepharon (adhesion of eyelids to the eyeball).
- Loss of normal eyelid margin structures e.g. madarosis (absence or loss of eye lashes).
- Dryness of eyes due to keratinisation.
Involutional or senile entropion is the most common type and affects lower lid only. Following age related changes contribute to involutional entropion.
- Overriding of pre-septal over the pre-tarsal part of orbicularis oculi muscle, during closure of eyelids. This moves the lower border of the tarsus away from the globe and the upper border toward the globe.
- Horizontal lid laxity produced by thinning and atrophy of the tarsus and the canthal tendons. Due to this laxity, middle part of lower lid when pulled away from the globe does not snap back to its normal position.
- Weakness of the lower lid retractors which can be assessed clinically by decreased excursion of the lower lid in down-gaze.
- Involution of the soft tissues of the orbit, particularly fat, may cause enophthalmos (deep seated eyes), which in turn lead to unstable eyelid position and entropion.
Cicatricial entropion is usually due to scarring of palpebral conjunctiva, which pull lid margin towards the eyeball. It is usually secondary to systemic and progressive inflammatory conditions.
Conditions which may lead to cicatricial entropion are:-
- Chemical burns of conjunctiva.
- Ocular cicatricial pemphigoid.
- Stevens-Johnson syndrome.
- Iatrogenic (induced inadvertently by medical professionals) e.g. following surgery, radiation therapy or use of chemotherapeutic drugs.
Acute Spastic Entropion:
Acute spastic entropion is produced due to spasm of orbicularis oculi muscle.
It may be:-
- Due to ocular irritation caused by infection, inflammation as in blepharitis, or trauma.
- Iatrogenic e.g. produced by surgical trauma.
- Essential blepharospasm.
True congenital entropion is rare.
It may be caused by:-
- Improper development of retractor aponeurosis insertion into the inferior border of the tarsal plate.
- Paucity of tissue may be present vertically in the posterior lamella of the eyelid.
- Tarsal kink syndrome produced by structural defects in the tarsal plate.
- Facial paralysis in children (unlike facial paralysis in adults which lead to ectropion).
Mechanism of entropion:
Lower lid is stabilised by orbicularis oculi muscle, tarsus, lower lid retractors and canthal tendons.
- Horizontal lid stability: Horizontal lid stability is provided by canthal tendons and tarsal plate. Loosening of horizontal tension leads to lid margin rotation.
- Vertical lid stability: Lower lid retractors provide vertical stability. Involutional entropion causes increased distance between lower lid retractors and inferior border of tarsal plate. Loosening of these vertical stabilising structure leads to inward lid rotation.
- Overriding of preseptal orbicularis oculi muscle: Lower lid retractors have fine extensions to orbicularis oculi muscle and to the overlying skin. Preseptal part overrides the pretarsal part of orbicularis oculi muscle due to weakness or dehiscence of the connections.This rotates eyelid margin against the globe.
- Orbital fat: Decrease in orbital fat content due to ageing or trauma causes enophthalmos, which increases space between eyelid and the eyeball. This produces lower lid laxity and greater orbicularis override.
Diagnosis depends upon elucidation of causative factors and clinical examination.
Examination may show features like:-
- Facial spasm, signs of skin irritation or infection.
- Examination of lid margin structures may show madarosis.
- Conjunctival examination may show dry eye features due to keratinisation induced by chronic irritation, symblepharon formation or forniceal (singular- fornix, where palpebral and bulbar conjunctiva meet) shortening.
- Cornea may show abrasion, scarring, thinning, neovascularisation or ulceration.
- Patient may show horizontal laxity of medial and/or lateral canthal tendons.
- Snap back test: Examiner pulls lower lid down and observes the lid returning to its original position without allowing patient to blink. Normally, lid returns back quickly without blinking, but in increased laxity, blink may be needed for its return to normal position. The examiner can also pull the lower lid anteriorly away from the globe. In involutional entropion, lid may be pulled away by 6-15mm from the globe, as compared to 2-3mm only in normal lid.
- Lower lid retractor function: This is evaluated by measuring lower lid excursion in downward gaze. Lower lid retractors cause 3-4mm inferior movement of lower lid margin in downgaze. This movement is absent or decreased in lower lid weakness, dehiscence or disinsertion.
- Eyelid eversion: In involutional entropion, lid can be everted easily.
- Conjunctival scar: Patients usually display scarring of conjunctiva.
- Lid traction: There is resistance to traction and persistence of entropion on horizontal lid traction.
- Eyelid eversion: Unlike involutional entropion, eyelid eversion is difficult.
Acute spastic entropion:
- In acute spastic entropion, forceful closure of eyelids may lead to overriding of preseptal over the pretarsal part of orbicularis oculi muscle.
- Congenital entropion shows inward turning of entire lower eyelid and lashes.
- There is absence of lower lid crease.
Entropion must be differentiated from conditions like:
- Trichiasis: Trichiasis is an acquired posterior misdirection of previously normal eye lashes. There is no inversion of the eyelid margin.
- Congenital distichiasis: In congenital distichiasis, there is partial or complete second row of eye lashes growing out of or slightly behind the meibomian gland orifices. Eye lashes in this condition are thinner, shorter and less pigmented than normal cilia (eye lashes).
- Acquired metaplastic eye lashes: Acquired metaplastic eye lashes may occur in late stages of Stevens-Johnson syndrome, trachoma and chemical burns. In this, eye lashes exit near the meibomian gland orifices and are associated with other changes such as keratinisation of the conjunctiva.
Congenital epiblepharon: Congenital entropion should be distinguished from more common congenital epiblepharon. Epiblepharon shows an extra horizontal fold of skin which stretches across the lid margin. The eye lashes may be turned upward, particularly medially. These may touch the cornea but they rarely cause discomfort in the eye. Pulling down the lid differentiates these conditions. In epiblepharon, the lashes turn out and the normal position of lid margin becomes visible. In congenital entropion, the entire eyelid is pulled away from the eyeball.
Management should be carried out under medical supervision.
Medical treatment may be needed in:-
- Patient who decline surgery.
- As temporising measure until patient can have surgery.
- Patient is too sick for surgical intervention.
- Patient who may improve spontaneously.
Medical non-invasive management may involve:-
- Taping of lower eye lid to malar (cheekbone) eminence.
- Application of cyanoacrylate liquid bandage to evert the eye lid.
- Botulinum toxin injection to the orbicularis oculi muscle may weaken it and help in prevention of override.
- Use of lubricating artificial tear preparations to protect ocular surface.
In spastic entropion, measures for blepharitis like lid hygiene, use of antibiotics and steroids may be useful in management.
- Various surgical procedures may be done e.g. application of cautery, lid rotational sutures, shortening of lower lid retractors, Wies and Fox procedure.
- Mild cases may be treated by tarsal fracture and severe cases may be treated with mucous membrane grafts.
Acute spastic entropion:
- Eyelid everting sutures may be applied.
- Tarsal fixation suture may prevent corneal damage.